Integrated genetic code expansion and structural bioinformatics reveal disrupted supramolecular assembly in a genetic disorder

ABSTRACT Deciphering the structural effects of variants is essential for understanding the pathophysiological mechanisms of genetic diseases. Using a neurodevelopmental disorder called Bosch-Boonstra-Schaaf Optic Atrophy Syndrome (BBSOAS) as a genetic disease model, we applied a combined Genetic Code Expansion (GCE) and structural bioinformatics strategy to assess the pathogenic impact of several human NR2F1 variants. Nonsense mutations in the ligand binding domain (LBD) resulted in truncated proteins, while missense variants significantly affected the folding of NR2F1 monomers as well as its supramolecular complexes. The GCE-enabled covalent and site-specific capture of transient supramolecular interactions in living cells revealed the variable quaternary conformations of NR2F1 variants and pinpointed the disrupted interplay with dimeric partners and the newly identified cofactor, CRABP2, while the computational analyses of the NR2F1 structure delineated the molecular basis of the impact of the variants on the isolated and complexed structures. The revealed consequence of the pathogenic mutations on the conformation, supramolecular interplay, and alterations in the cell cycle, viability, and subcellular localization of the different variants reflect the heterogeneous disease spectrum and establish the foundation for further understanding the complexity of BBSOAS.